Introduction
Gonadorelin hydrochloride, with the same amino acid sequence as endogenous gonadorelin, which is Pro-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2, is one of the commercially available gonadotropin releasing hormone (GnRH) analogues and agonists. Almost all of the GnRH analogues and agonists are considered to have good stability and capacity to bind plasma proteins and GnRH receptors and have been developed as effective drugs widely applied in a lot of clinical uses especially the manipulation of ovarian functions. Among them, gonadorelin hydrochloride has been proved to be an ideal choice for the treatment of ovarian follicular cysts in cows.
Pharmacologic action
Ovarian follicular cysts, the essence of which is the abnormal follicular maturation and ovulation, is one of the most common causes of impairing reproductive efficiency of cows. The main reason for the occurrence of ovarian follicular cysts is that the surge of luteinizing hormone (LH) is absent in the pre-ovulation period. Therefore, the treatment target of ovarian follicular cysts is exogenous administration of any product possessing LH activity, such as pregnant mare's serum gonadotropin (PMSG) or human chorionic gonadotropin (HCG) to trigger ovulation or regression of follicular cysts. Gonadorelin hydrochloride works by inducing a LH response similar to the preovulatory LH surge to produce the same effect as the above products.
Function
Gonadorelin hydrochloride, one of GnRH analogues and agonists also named factrel, possesses a wide range of applications. It is well recognized that gonadorelin hydrochloride can be used to treat ovarian follicular cysts in cows successfully. In addition to the above, gonadorelin hydrochloride is also a powerful tool for studying follicular and luteal dynamics, as well as the determination of LH secretion.
Pharmacokinetics and metabolism
There are several kinds of administration forms available for gonadorelin hydrochloride. For the treatment of ovarian follicular cysts in cows, gonadorelin hydrochloride is generally injected into body with intramuscular route of administration. The administration of gonadorelin hydrochloride doesn't affect any physiological or clinical parameter. Meanwhile, there is no evidence that gonadorelin hydrochloride will result in irritation at injection site in any animal. Thus gonadorelin hydrochloride is a safe drug without any objection.
References:
Monnoyer S, Guyonnet J, Toutain P L. A preclinical pharmacokinetic/pharmacodynamic approach to determine a dose of GnRH, for treatment of ovarian follicular cyst in cattle[J]. Journal of Veterinary Pharmacology & Therapeutics, 2004, 27(6):527–535.
Martínez M F, Mapletoft R J, Kastelic J P, et al. The effects of 3 gonadorelin products on luteinizing hormone release, ovulation, and follicular wave emergence in cattle[J]. Canadian Veterinary Journal, 2003, 44(2):125-131.
Kaneko H, Todoroki J, Noguchi J, et al. Perturbation of Estradiol-Feedback Control of Luteinizing Hormone Secretion by Immunoneutralization Induces Development of Follicular Cysts in Cattle1[J]. Biology of Reproduction, 2002, 67(6):1840-1845.
Drost M, Thatcher W W. Application of gonadotrophin releasing hormone as therapeutic agent in animal reproduction[J]. Animal Reproduction Science, 1992, 28(1):11-19.
